| arthropod by-products |
- cast skins (translucent or whitish): aphids, leafhoppers, lace bugs, spider mites
- dark fecal specks: lace bugs, leafminer adults, plant bugs, shore fly adults, thrips
- flocculence (cottony, waxy material): adelgids, certain aphids, lerp psyllids, mealybugs, certain scale insects, whiteflies
- large excrement (frass) particles: caterpillars, leaf beetles
- pale foam or spittle: spittlebugs
- pitch masses: larvae of certain moths e.g., Sequoia pitch moth
- pitch tubes: certain bark beetles (Scolytinae)
- shiny trails or slime: fungus gnat larvae, slugs, snails
- silken mats, tents, or webs or rolled leaves: leafrollers, tent caterpillars, webworms
- sticky honeydew and blackish sooty mold: aphids, mealybugs, psyllids, soft scales, whiteflies
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| bleached, bronzed, stippled, or yellowed foliage |
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| chewed or tattered blossoms or foliage |
- adults and larvae of leaf-feeding beetles
- crickets, grasshoppers, or katydids
- larvae (caterpillars) of butterflies and moths (Lepidoptera) e.g., armyworms, cabbage looper, cutworms, diamondback moth, European pepper moth (Dufo moth)
- larvae of sawflies (broad-waisted wasps) e.g., rose slugs
- leafcutting bees, which are important pollinators and should not be killed. Where these bees have been collecting material for their nests covering those plants with cheesecloth or other screening prevents further damage. Place out these barriers when leaf cutting is first observed or the time of year (late winter or spring) when damage first occurred during previous seasons. Barriers can be removed about midsummer when the mother bees are no longer active.
- snails or slugs e.g., brown garden snail
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| dieback of plant parts |
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| distortion of plant parts |
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| foliage mines |
- larvae of certain flies, moths, or sawflies (broad-waisted wasps)
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| holes in stems, bark or twigs |
- adult beetles e.g., bark beetles, flatheaded borers, longhorned beetles
- larvae of boring beetles or caterpillars (e.g., clearwing moths) feeding hidden in plants
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| Adapted from Container Nursery Production and Business Management Manual, UC ANR Publ. 3540 |